KLH 20/20+ speaker schematics?

[Guest lecanardnon]

Hi all,

I've put together a ramshackle Twenty Plus system in pieces, and now that I have it all in one place, I'm planning to refinish all the cabinets, maybe replace the grungy turntable with parts from a stock Twenty, etc.

I'd also like to take a plunge at recapping the speaker crossovers also, which I've never done before, but seems like a fun starter project. Problem is, I can't find a schematic for these speakers anywhere. I haven't pulled open the cases yet as I'm actually using them and would like to order parts before dismantling. I know 20+ speakers should be the same as 20 speakers, which are in turn a 4ohm version of the 17s, but I still don't seem to have enough information to go get the right parts. Don't want to blow anything up.

Anyone?

Thanks!

Ben

[JKent]

Hi all,
I've put together a ramshackle Twenty Plus system in pieces, and now that I have it all in one place, I'm planning to refinish all the cabinets, maybe replace the grungy turntable with parts from a stock Twenty, etc.

I'd also like to take a plunge at recapping the speaker crossovers also, which I've never done before, but seems like a fun starter project. Problem is, I can't find a schematic for these speakers anywhere. I haven't pulled open the cases yet as I'm actually using them and would like to order parts before dismantling. I know 20+ speakers should be the same as 20 speakers, which are in turn a 4ohm version of the 17s, but I still don't seem to have enough information to go get the right parts. Don't want to blow anything up.

Anyone?

Thanks!
Ben

I've recapped both the 17 and 20, as as you said they are identical except for the impedance of the woofer. Here is the schematic for the 17. 20 is the same. Don't be confused when you open it up and see only 2 caps--one is a double 2uF. Just replace that with two 2uF caps. you need two 2uf and one 8uf per speaker. good luck.
Kent

btw DO replace those caps! They are Callins red & black PVC and they leak and/or explode!

[Guest lecanardnon]

JKent: Thanks for the info and schematic. I had assumed that the differing impedence on the woofers would mean different caps, but it sounds like that's not true. Thanks for the info!

[Guest lecanardnon]

I got down to this project finally this weekend, did the left speaker (right one to follow). First of all, the 20+ has the crossover mounted on the bottom rear of the case unlike the 17 (or the 20, I imagine). A bit tricky to work with.

More importantly, the schematic for this speaker isn't like the one you posted, JKent. There was only a single capacitor, a dual 2UF (marked "Whale My-Lytic 2UF 50V"). The 8UF one simply wasn't there at all. Presumably this is because the overall impedence of the system is different?

Anyways, I went ahead and replaced the dual cap with 2x2UF caps, and sealed it all back up. It sounds OK-- a little clearer in the highs, but seems to have lost some bass response relative to the other (stock) speaker. Not a scientific study, of course, but flipping the balance back and forth shows a clear difference in bass clarity.

Could reduced bass be related at all to the work that I did on the speaker? I hear occasional buzzing (only on this speaker) with really pure bass (Kanye West's "Love Lockdown" turns out to be a good test). I suspect that's something physical with the woofer, but unsure. (Unfortunately didn't do a control test before opening it up.)

Anyone have thoughts or comments?

Cheers.

[JKent]

More importantly, the schematic for this speaker isn't like the one you posted, JKent. There was only a single capacitor, a dual 2UF (marked "Whale My-Lytic 2UF 50V"). The 8UF one simply wasn't there at all. Presumably this is because the overall impedence of the system is different?

No--it's in there. It just is not with the other cap. Follow the blue wire from the switch or the red wire from the tweeter and you will find it. According to KLH's literature, the Model Twenty Plus is identical to the Model Twenty, except for the fancier cabinets. Photo on the left below shows 8uF in a Model Twenty.
Reduced bass: Did you seal the speakers drivers to the cabinet when you reassembled it? I don't know if the 20+ uses foam gaskets or gooey duct-seal type sealant but you need a good seal. And I assume you put all the fiberglass back in.
Are you sure you installed the caps correctly? You should have used either film caps or NON-POLAR electrolytics. Using polarized caps is a no-no. One lead of each cap is twisted together and attached to the + terminal, along with one lead from one 3 ohm resistor and the red wire from the woofer. The other lead from one cap goes to the "increase" position on the switch while the other lead from the other cap goes to the "normal" position. Photo on the right below shows a rebuilt KLH Seventeen crossover.
Do you have decreased bass with the switch in all 3 positions?
Buzzing could be a bad driver. They are common on ebay but I'm not sure that it is bad.
Good luck.
Kent

[Guest lecanardnon]

No--it's in there. It just is not with the other cap. Follow the blue wire from the switch or the red wire from the tweeter and you will find it. According to KLH's literature, the Model Twenty Plus is identical to the Model Twenty, except for the fancier cabinets. Photo on the left below shows 8uF in a Model Twenty.

Reduced bass: Did you seal the speakers drivers to the cabinet when you reassembled it? I don't know if the 20+ uses foam gaskets or gooey duct-seal type sealant but you need a good seal. And I assume you put all the fiberglass back in.

Are you sure you installed the caps correctly? You should have used either film caps or NON-POLAR electrolytics. Using polarized caps is a no-no. One lead of each cap is twisted together and attached to the + terminal, along with one lead from one 3 ohm resistor and the red wire from the woofer. The other lead from one cap goes to the "increase" position on the switch while the other lead from the other cap goes to the "normal" position. Photo on the right below shows a rebuilt KLH Seventeen crossover.

Do you have decreased bass with the switch in all 3 positions?

Buzzing could be a bad driver. They are common on ebay but I'm not sure that it is bad.

Good luck.

Kent

Kent--

Thanks for the timely reply! I completely assumed the inline component that was on the wire to the tweeter was a resistor of some kind to protect the tweeter, and I just didn't even bother looking closely at it since I didn't need to to do the work. I'll have to open 'er back up and double check. I was going off the visual guide of the 17 rebuild that's elsewhere on this site-- those capacitors look very different from the one(s) I found, hence the confusion.

Anyways, the non-upgraded cap might help explain some of the sound issues, although there's no reason to assume the stock cap is busted. I used Dayton caps from parts express, so I assume I'm good on those. The wiring is correct, although I'm not a pro solder-er, and the angle was tricky-- is it possible that impure connection would lead to reduced bass (rather than no sound at all)?

I didn't re-dope the surrounds (yet) but I did seal the driver with rope caulk (which was what it had been sealed with originally. All insulation is back in the ole box. So I don't think it's related to the cabinet seal.

I'm keeping my eye out on eBay for a replacement woofer (although the 20/20+ ones are more scarce than the 17s and 6s, etc, and the 20s have to be cut to fit :\ ) The best empirical test will be to swap the woofer from the other speaker in when I start on that one, and see if it changes the sound-- if so, the woofer's supbar. If not, something was subpar with the work on the crossover...

[JKent]

Kent--

Thanks for the timely reply! I completely assumed the inline component that was on the wire to the tweeter was a resistor of some kind to protect the tweeter, and I just didn't even bother looking closely at it since I didn't need to to do the work. I'll have to open 'er back up and double check. I was going off the visual guide of the 17 rebuild that's elsewhere on this site-- those capacitors look very different from the one(s) I found, hence the confusion.

Anyways, the non-upgraded cap might help explain some of the sound issues, although there's no reason to assume the stock cap is busted. I used Dayton caps from parts express, so I assume I'm good on those. The wiring is correct, although I'm not a pro solder-er, and the angle was tricky-- is it possible that impure connection would lead to reduced bass (rather than no sound at all)?

I didn't re-dope the surrounds (yet) but I did seal the driver with rope caulk (which was what it had been sealed with originally. All insulation is back in the ole box. So I don't think it's related to the cabinet seal.

I'm keeping my eye out on eBay for a replacement woofer (although the 20/20+ ones are more scarce than the 17s and 6s, etc, and the 20s have to be cut to fit :\ ) The best empirical test will be to swap the woofer from the other speaker in when I start on that one, and see if it changes the sound-- if so, the woofer's supbar. If not, something was subpar with the work on the crossover...

OK--you used good caps, replaced the rope caulk and the fiberglass. Three points for the good guys Re-doping may not be necessary but take a look at the surrounds and see if the old stuff has come off. If so, RoyC has some new formula to try, but the surrounds are probably fine.

I have never seen a Plus up close & personal. What do you mean the woofer would have to be cut? Does the Plus use a "truncated" woofer (flat sides)? If the woof is bad and you cannot find a replacement, everyone here swears by Bill Legall of Millersound.

http://www.millersound.net/about.htm

He should be able to repair an ailing woofer if it is something like a disconnected cone or voice coil rub. But yes--do your empirical test first.

Don't rule out a cold solder joint or bad cap (although the 8uF is the tweter cap). Those red&black PVC caps are NOTORIOUS for failing and/or exploding! I usually call them "craps"

Good luck

Kent

[Guest lecanardnon]

Here's a puzzler for you, Kent.

Replacing the tweeter cap in either of the speakers causes no sound to come from the drivers at all! I tried in one, then the other speaker and got the same result-- zero output at all. The cap I'm replacing is fairly small, and marked as 8MFD-50V, which I read as being 8uF. (I'm replacing with the Dayton 8.2uF caps, which is the closest they got.)

Any thoughts on why this might be the case? What am I missing?

Thanks.

[JKent]

Hmmmm... I'm stumped but have asked a couple of experts to have a look

[JKent]

Replacing the tweeter cap in either of the speakers causes no sound to come from the drivers at all! I tried in one, then the other speaker and got the same result-- zero output at all. The cap I'm replacing is fairly small, and marked as 8MFD-50V, which I read as being 8uF. (I'm replacing with the Dayton 8.2uF caps, which is the closest they got.)

OK--I'm not an engineer, but if the problem only arises when you replace the cap, it has to be the cap (or the solder connection)
Please give me the Parts Express part number of the cap. Is it 027-426? This one? http://www.parts-express.com/pe/pshowdetl.cfm?PartNumber=027-426'>http://www.parts-express.com/pe/pshowdetl....tNumber=027-426
You may have a cold solder joint.
It's possible that you soldered the cap to the wrong place on the switch.
The speakers worked before you replaced the 8.2uF cap but not after, so SOMETHING involved in replacing that cap must be the culprit. Re-check all the wiring and please be sure to let me know the PE part # of the cap. It is also possible that the cap is bad but almost impossible that TWO new caps would be bad.

Let me just say that before joining this forum I (like you) could not tell the difference between a capacitor and a resistor. You probably made a very simple mistake here, as we all have, so just re-trace everything step by step. As an aside: Last week I had an experience right out of the movie "Christmas Vacation." My TV and internet went out during a storm. Came back about an hour later, but the next day it was out again. Cable Co said the problem had been fixed but they would schedule a service call (for a price). I wound up pulling the cover off my electric panel, tracing wires, replacing an outlet (the signal amplifier was getting no power) and pulling my hair. After hours of investigation I discovered the outlet the amp was plugged into was SWITCHED and a guest had flipped the switch off the night before!

So...to err is human

Good luck
Kent

[Guest lecanardnon]

OK--I'm not an engineer, but if the problem only arises when you replace the cap, it has to be the cap (or the solder connection)

Please give me the Parts Express part number of the cap. Is it 027-426? This one? http://www.parts-express.com/pe/pshowdetl....tNumber=027-426

You may have a cold solder joint.

It's possible that you soldered the cap to the wrong place on the switch.

The speakers worked before you replaced the 8.2uF cap but not after, so SOMETHING involved in replacing that cap must be the culprit. Re-check all the wiring and please be sure to let me know the PE part # of the cap. It is also possible that the cap is bad but almost impossible that TWO new caps would be bad.

Thanks Kent. I'm also not an electric engineer, and have made some boneheaded mistakes before, so it would seem like I am doing so here again. Having trouble figuring out what it is in this case. The link you gave is indeed the part that I have, one for each speaker. And indeed I had the same problem with both speakers. (no sound from either when the 8.2uF was installed). Those caps aren't soldered in in my crossovers, they're just inline on the tweeter's + (red) lead using the wire twist-on plastic caps (forget what these are called). This was the way the original ones were attached on there. Now, I suppose the original components here could be resistors instead of caps, but that would leave the crossover without any 8uF caps, and also the markings (8MFD-50V) looks unlikely to be a resistor. When I put back the original component inline to the tweeter, the speaker immediately started working again. Weird!

In any case, I can go on and call it "ok" with the original parts in there, since the sound is still overall acceptable, but I am curious as to what's happening here, given how many folks seem to have successfully used these same replacement parts in identical circuits.

[JKent]

Thanks Kent. I'm also not an electric engineer, and have made some boneheaded mistakes before, so it would seem like I am doing so here again. Having trouble figuring out what it is in this case. The link you gave is indeed the part that I have, one for each speaker. And indeed I had the same problem with both speakers. (no sound from either when the 8.2uF was installed). Those caps aren't soldered in in my crossovers, they're just inline on the tweeter's + (red) lead using the wire twist-on plastic caps (forget what these are called). This was the way the original ones were attached on there. Now, I suppose the original components here could be resistors instead of caps, but that would leave the crossover without any 8uF caps, and also the markings (8MFD-50V) looks unlikely to be a resistor. When I put back the original component inline to the tweeter, the speaker immediately started working again. Weird!

In any case, I can go on and call it "ok" with the original parts in there, since the sound is still overall acceptable, but I am curious as to what's happening here, given how many folks seem to have successfully used these same replacement parts in identical circuits.

Definitely not resistors. 8MFD-50V means 8 microfarads 50 volts. The 8.2uF (microfarad) 250 volt poly Dayton should work perfectly. So a red wire goes from the tweeter's + terminal to one lead of the cap. The other lead from the cap is attached to the (blue?) wire that goes to the switch, right? Did you try the switch in different positions? Are you sure you have a good connection with the wire nuts? It is very weird, since it works when you put the old caps back in. The bare wire leads on the Daytons aren't shorting against anything, are they? Worst case scenario you could mail me your Daytons for me to check with an LCR meter.

Kent